Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Protein Quantification (Serum/Plasma)
This test measures the amount of CFTR protein in your blood, which helps assess how well your body produces this protein linked to cystic fibrosis.
["CFTR protein levels can indicate potential cystic fibrosis-related issues or monitor treatment effects."]
Key facts at a glance
- LOINC
- 38454-5
- Short code
- CFTRG85E
- Synonyms
- CFTR p.G85E Bld/T Ql
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender/purple-top) tube for whole blood; sterile container for tissue specimens
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–999 years
- Method
- molgen
- CPT
- 81223
- SNOMED
- 5304004
- Specimen volume
- 3-5 mL whole blood in EDTA tube; minimum 1 mL for pediatric samples. Tissue: minimum 5 mg in sterile saline or transport medium.
- Stability
- Whole blood: stable for 7 days at 2-8°C; 3 days at room temperature (15-25°C); long-term storage at -20°C or below. Tissue: stable for 24 hours at room temperature in transport medium; 7 days at 2-8°C.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 168–720 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may order this test if you have symptoms of cystic fibrosis, a family history of the condition, or if you’re being evaluated for genetic testing. It may also be used to monitor CFTR-related disorders or evaluate responses to therapies targeting CFTR.
What to Expect Before the Test
No special preparation is typically needed. You may have a blood draw from a vein in your arm, similar to other blood tests. If you’re on blood thinners, inform your provider beforehand.
What the Test Results Mean
Results show the concentration of CFTR protein in your blood. Lower than expected levels may suggest genetic mutations affecting CFTR production or function, which could relate to cystic fibrosis or other conditions. Results alone don’t diagnose cystic fibrosis; they’re often used alongside genetic testing or clinical symptoms.
Common Causes of Abnormal Results
Abnormal CFTR protein levels can result from genetic mutations causing cystic fibrosis or other CFTR-related disorders. They may also appear in conditions affecting protein synthesis, liver disease, or certain metabolic disorders. Always discuss results with your provider for personalized interpretation.
Reference range
Negative for CFTR p.Gly85Glu mutation (wild-type genotype). This is a qualitative test reporting presence or absence of the specific CFTR gene variant.N/A
No fasting required. Informed consent for genetic testing is recommended per institutional policy. Genetic counseling is advised before and after testing.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CFTR Protein Level
Frequently asked questions
How often do I need this test?
What if my results are low?
Can diet or medications affect this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy